[51] I agree with Bridgeview that the 334 patent discloses a combination invention. It is not fair to a person claiming to have invented a combination invention to break the combination down into its parts and find that, because each part is well known, the combination is necessarily obvious: see, for example, Stiga Aktiebolag v. S.L.M. Canada Inc. (1990), 34 C.P.R. (3d) 216 at page 245 (F.C.T.D.), which quotes this passage from Wood & Amcolite Ltd. v. Gowshall Ltd. (1936), 54 R.P.C. 37 at page 40 (per Greene L.J.):

The dissection of a combination into its constituent elements and the examination of each element in order to see whether its use is obvious or not is, in our view, a method which ought to be applied with great caution since it tends to obscure the fact that the invention claimed is the combination. Moreover, this method also tends to obscure the facts that the conception of the combination is what normally governs and precedes the selection of the elements of which it is composed and that the obviousness or otherwise of each act of selection must in general be examined in the light of this consideration. The real and ultimate question is “Is the combination obvious or not?”

[52] The invention claimed in the 334 patent is not simply the use of a gear box to change the direction of a tractor’s power take off. The claimed invention includes the use of a gear box for that purpose, but only in combination with the other essential elements, resulting in a bale processor that disintegrates the bale in a particular way and discharges the disintegrated material in a particular way to the right. The question the judge should have asked, but did not, is whether the common general knowledge that he identified would have led the skilled but uninventive person to come directly and without difficulty to the particular combination of elements of the invention disclosed in the 334 patent, as construed by the judge.

[53] The evidence on this question that most favours the position of Duratech is found in the opinion of Dr. Parish. He opined that, given knowledge of the Hesston BP 20, it would have been obvious to a person skilled in the art who wished to design a right hand discharge bale processor to use a gear box or other reversing mechanism, combined with a right discharge opening, and that there was motivation to do so in light of the trend in the industry to right hand discharge for farm machinery pulled by tractors. This opinion, unlike Dr. Parish’s opinion on patent construction and infringement, is weakened by the absence of supporting analysis. Indeed, it is little more than a bare conclusion. For example, it does not explain why at the relevant time, no one except the inventor of the Bale King had managed to produce a commercially successful right hand discharge bale processor. As mentioned above, the Hesston BP 20 was not commercially successful. It is reasonable to infer that the successful development of a right hand discharge bale processor required more than simply adding a reversing gear box to an existing bale processor.

[54] On the question of obviousness, Duratech cited in argument two additional items of prior art, namely U.S. patents 4,830,292 and 4,879, 810 (the “Frey patents”), which are patents for bale processors that pre-date the 334 patent. Indeed, U.S. patent 4,830,292 is disclosed in the 334 patent. I was able to find in the record no expert opinion construing these U.S. patents, but on a literal reading they appear to relate, in the one case, to a particular kind of cutting device in place of flails for disintegrating the bale, and in the other case, to an improvement in the means for manipulating the bale. I can find no mention in either U.S. patent of right hand discharge. Duratech says that these patents teach right hand discharge because they “implicitly” have a reversing gear. However, I am unable to discern from the patent alone whether that assertion is valid, and Duratech has not cited any evidence on the point.

[55] I conclude that the judge erred in law when he held that, given the state of the art at the relevant time, the skilled but uninventive person would have been led directly and without difficulty to the solution taught by the 334 patent. For that reason, the judge’s conclusion as stated in paragraph 68 of his reasons cannot stand. I would allow the appeal on that issue.